SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fd172af2c507fbe464511434935d266d427db013ee36f770cc417d1dd9dc8c3' 
  AND token = 'S6G4w7TjkBb3gnXBFpPxlE6WJnCdrH7EimaFydvJazM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}